DERIVATIVE FINANCIAL INTSTRUMENTS - Summary of Outstanding Swaptions (Details) - Payer Swaption [Member] - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2020	Dec. 31, 2021
Long [Member]
Derivatives, Fair Value [Line Items]
Swaption Cost	$ 47,205		$ 36,690
Net Estimated Fair Value	$ 60,362		21,493
Derivative Instruments Average Months To Expiration	14 months	14 months 21 days
Notional Amount	$ 2,010,800		$ 400,000
Derivative Average Fixed Interest Rate	2.47%		2.27%
Term (Years)	10 years 9 months 18 days	11 years 10 months 24 days
Less Than Or Equal To One Year [Member] | Short [Member]
Derivatives, Fair Value [Line Items]
Swaption Cost	$ 19,540		$ 16,185
Net Estimated Fair Value	$ 25,535		4,423
Derivative Instruments Average Months To Expiration	5 months 24 days	5 months 9 days
Notional Amount	$ 1,433,000		$ 1,331,500
Derivative Average Fixed Interest Rate	2.47%		2.29%
Term (Years)	10 years 9 months 18 days	11 years 4 months 24 days
Less Than Or Equal To One Year [Member] | Long [Member]
Derivatives, Fair Value [Line Items]
Swaption Cost	$ 31,905		$ 4,000
Net Estimated Fair Value	$ 33,040		1,575
Derivative Instruments Average Months To Expiration	11 months 9 days	3 months 6 days
Notional Amount	$ 1,282,400		$ 1,258,500
Derivative Average Fixed Interest Rate	2.44%		1.66%
Term (Years)	11 years 3 months 18 days	5 years
One Year To Two Years [Member] | Long [Member]
Derivatives, Fair Value [Line Items]
Swaption Cost	$ 15,300		$ 32,690
Net Estimated Fair Value	$ 27,322		19,918
Derivative Instruments Average Months To Expiration	18 months 24 days	18 months 12 days
Notional Amount	$ 728,400		$ 1,658,500
Derivative Average Fixed Interest Rate	2.52%		2.46%
Term (Years)	10 years	14 years 1 month 6 days